As this kind of the exhaust gas analysis system there is an exhaust gas analysis system that measures carbon monoxide (CO), total hydrocarbons (THC), nitrogen oxide (NOx), and carbon dioxide (CO2) contained in an exhaust gas emitted from, for example, an engine of an automobile.
Concretely, the above-mentioned exhaust gas analysis system has an exhaust gas flow line where the exhaust gas of the engine flows, and a measurement device that is arranged in the exhaust gas flow line and that measures various components contained in the exhaust gas flowing in the exhaust gas flow line.
Conventionally as shown in the patent document 1, in order to remove the pollutant in the exhaust gas flow line in the upstream side of the measurement device, a purge is conducted by supplying a large amount of a clean purge gas in a pressurized state to the exhaust gas flow line in the upstream side of the measurement device so as to remove a residual material (pollutant component) that attaches to or resides in each part of the exhaust gas flow line after measuring the exhaust gas for the above-mentioned exhaust gas analysis system.
However, there is a problem that there is a user who forgets to conduct the purge after measuring the exhaust gas. In addition, there is a problem that there is a user who does not conduct the purge because the user considers there is no problem even though the purge is not conducted every time the exhaust gas measurement is completed if an error of the exhaust gas measurement is negligibly small. As mentioned, if the exhaust gas measurement is conducted without conducting the purge after completion of the exhaust gas measurement, a measurement error generates because the pollutant component that attaches to or resides in the exhaust gas flow line at a time of a previous exhaust gas measurement is measured in the following exhaust gas measurement. In addition, it is difficult to objectively judge whether the measurement error is negligibly small or not so that it is not possible to judge whether the measured concentration of the pollutant component is due to increase of the concentration of the pollutant component contained in the exhaust gas or the measured concentration of the pollutant component is due to the pollutant component that attaches to or resides in the line.
As mentioned, it is a situation that whether the purge is necessary to be conducted or not is judged objectively by a user and that the purge is conducted every time the exhaust gas measurement is completed is considered to be the most reliable method to reduce the measurement error. In other words, the user selects arbitrarily whether the purge is conducted every time the exhaust gas measurement is completed or not by comparing a merit that the measurement error is reduced due to conducting the purge with a demerit that a number of operation increases due to conducting the purge.